Refractory submillimeter Josephson effect sources

Niobium Josephson effect array oscillators have been fabricated and tested. These devices deliver about 1 mu W of power in the submillimeter-wave range to 20-60 Omega load resistors. The present upper frequency limit of about 500 GHz appears to be set by losses in the superconducting microstrip. Data on the submillimeter-wave surface impedance of the niobium microstrip and details of the trilayer junction processing, which gives value of V/sub m/ at 2 K up to 800 mV, are presented.